/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.editor;

import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.*;

/**
 * This AttributeVisitor computes and updates the maximum local variable frame size of the code attributes that it
 * visits. It also cleans up the local variable tables.
 *
 * @author Eric Lafortune
 */
public class VariableSizeUpdater extends SimplifiedVisitor implements AttributeVisitor, InstructionVisitor {
    // *
    private static final boolean DEBUG = false;
    /*/
    private static       boolean DEBUG = true;
    //*/

    private VariableCleaner variableCleaner = new VariableCleaner();

    // Implementations for AttributeVisitor.

    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}

    public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
        // DEBUG =
        // clazz.getName().equals("abc/Def") &&
        // method.getName(clazz).equals("abc");

        // The minimum variable size is determined by the arguments.
        codeAttribute.u2maxLocals =
            ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz), method.getAccessFlags());

        if (DEBUG) {
            System.out.println(
                "VariableSizeUpdater: " + clazz.getName() + "." + method.getName(clazz) + method.getDescriptor(clazz));
            System.out.println("  Max locals: " + codeAttribute.u2maxLocals + " <- parameters");
        }

        // Go over all instructions.
        codeAttribute.instructionsAccept(clazz, method, this);

        // Remove the unused variables of the attributes.
        variableCleaner.visitCodeAttribute(clazz, method, codeAttribute);
    }

    // Implementations for InstructionVisitor.

    public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset,
        Instruction instruction) {}

    public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset,
        VariableInstruction variableInstruction) {
        int variableSize = variableInstruction.variableIndex + 1;
        if (variableInstruction.isCategory2()) {
            variableSize++;
        }

        if (codeAttribute.u2maxLocals < variableSize) {
            codeAttribute.u2maxLocals = variableSize;

            if (DEBUG) {
                System.out.println(
                    "  Max locals: " + codeAttribute.u2maxLocals + " <- " + variableInstruction.toString(offset));
            }
        }
    }
}
